Ha-young faces dangerous criminals and struggles to see through them. He digs into the thoughts and intentions of those who commit evil crimes and follows in the footsteps of what made them fall into the abyss of evil.

A part of a victim's body is found in an alley, and a report of the disappearance of a five-year-old girl, Lee Soo-young, is received.

The Behavioural Analysis Team and Special Crime Squad join forces to search for the body of a missing girl.

Ha-young and Young-su have an interview with Jo Hyeon-gil. Soon, the two try to look inside his head, but are confused by the unbearable aura of evil.

Ha Young and Young Soo continue the search for the prime suspect in an elderly murder case. The team suspect a murder in Hwanghwa-dong is connected.

A murderer who committed a crime against a wealthy elderly person disappears, and another murder case occurs that is similar but differs in method. Ha-young struggles to uncover the identity of the culprit.